1. Field of the Invention
The present invention relates to a distance measuring device and a camera provided with this distance measuring device, and further relates, for example, to a distance measuring device such as a still camera, video camera and the like, and an input device such as an image recognition device and the like.
2. Description of the Related Art
Various conventional cameras have been proposed which recognize a main object as a main object for photography, and automatically set the focus and exposure of the object.
In this case, although the distance to the main object to be focused is determined from measurement information, the measurement data are not necessarily measurement data having high reliability. For example, U.S. Pat. No. 5,068,737 discloses art which accomplishes focus adjustment using data having high reliability as a method of focus adjustment in these cases. In addition, Japanese Laid-Open Patent Application No. 11-119088 discloses a focus adjustment method for focusing when data reliability is low.
When recognizing a main object as a basis of distance information regarding the object, consider a plurality of measurement areas are arranged, and the field of the main object is recognized as a basis of distance data of each measurement area, and recognizing the main object from the field information.
In the case of passive type distance measuring systems, however, accurate distance measurement data cannot be obtained with regard to, for example, parts of the object having low contrast, parts of the object which are dark, parts of the object having different distances but included in the same distance measuring area, and parts of the object which are too bright.
In the case of active type distance measuring systems, accurate distance measurement data cannot be obtained with regard to, for example, parts of the object having low reflectivity, parts of the object having direct reflection, parts wherein reflectivity varies within the illumination range of the distance measuring beam and the like.
When accurate distance measurement data cannot be obtained due to such theoretical problems, for example, the distance to part of the object cannot be measured. For this reason main object recognition may be impossible or erroneous recognition may occur because separate divisions of the object may be recognized despite the fact it is a single object.
Accordingly, the problems of the art solved by the present invention are overcome by providing a distance measuring device capable of accurately recognizing an object even when a part of the object cannot be accurately measured.